Method for treating oil



` Rjc. osTERsTRCM Nove 29, 1938.

Y METHOD FOR TREATING OIL 2 Sheets-Sheet l Filed Oct. 5, 1934 Nov. 29, 1938. Ric. osTERsTRoM 2,138,770

METHOD FOR TREATING OIL \//-/Vace 159 1 Ttig/'211026779 cepmfof y Y 145 Ely Z INVENTORl f Elftal/uk flerrlmm ATTORNEY Patented Nov. 29, 1938 UNITED STATES METHoD Fon. TREATING oIL Rudolph C. Oster-strom, Kenilworth, Ill., assgnor to The Pure Oil Company, Chicago, Ill., a corporation oi Ohio Application October 5,

11 Claims.

This invention relates tothe manufacture of gasoline motor fuel of a desired anti-knock value or boiling range, or both, and of desired purity and stability with respect to colorand gum- 5 forming constituents, from gasoline or naphtha,

produced either by simple distillation or by pyrolysis .from petroleum or petroleum oils, and of less desirable characteristics.

My invention has for an object the provision of a method and apparatus whereby conversion of a naphtha or gasoline to a product of improved characteristics as to anti-knock value or boiling range or both, and purication of the resultant product from unstable impurities formed as an incident to such conversion may be effected in an advantageous manner.

A further object of my invention is to provide a method and apparatus for cracking and rening heavier oils such as kerosene and gas oil.

More particu1arly,.the invention is directed to av continuous process and apparatus wherein gasoline or naphtha is subjected to conversion conditions of temperature and pressure to reform the same and the converted products are, preferably in their entirety, subjected to subsequent treatment with a polymerized catalyst,

- while at elevated temperature and preferably also under superatmospheric pressure, to effect the conversion of undesirable gum-forming constituents to products of higher. boiling point, which can readily be removed from the desired product.

In accordance with my invention, a gasoline, naphtha, kerosene or gas oil which it is desired to improve is passed through a confined zone under high pressures and temperatures for a period of time sufcient to convert the stock into gasoline of increased anti-knock rating or of modified boiling range, or both, andthe prod? 40 ucts leaving the conversion zone are immediately thereafter chilled to a temperature below a conversiomtemperature, as for example by means of direct contact with hydrocarbon oil, such as refined light stock previously produced by the process or other refined or unrefined oil, either light or heavy. The products are then passed with or without substantial reduction of pressure and with or without further heating through a 50 treating zone where they are subjected to contact with'a solid adsorptive catalyst eective to polymerize gum-forming constituents `to'heavy polymers. 'I'he latter are then removed from the light distillate by fractionation, preferably under reduced pressure.

In one form of the invention the entire products from the heat and pressure conversion zone are passed through the treating zone without previous reduction of pressure to any substantial degree, whereby highly ecient operation .of the 1934, Serial No. 747,015

clay tower is obtained, together with other operative advantages.

The invention will be more fully understood from the following description taken in connec tion with the accompanying drawings, in which Fig. 1 is a diagrammatic side elevation of an apparatus embodying the principles of the invention when carrying out clay treatment under high pressure and preferably in the liquid phase, and

Fig. 2 is a diagrammatic side elevation of an apparatus embodying the principles of my invention as adapted to vapor-phase clay treatment.

Referring to Fig. 1, the numeral I indicates a tank or source of supply of charging stock, for example heavy cracked naphtha, straight run gasoline, kerosene, gas oil or the like. A line 2 having valve 3, booster pump 4, and high pressure pump 5 connected therein leads to a heating coil 6. The heating coil 6 is located in the hottest portion of a heating chamber 1 forming part of a furnace 8. A line 9 leads to an arrester I0. The arrester I0 is connected to a second arrester II by means of pipe I2 controlled by valve I3. A by-pass line I4 controlled by valve I5 connects lines 9 and I2. A withdrawal pipe I6 controlled by valve I1 is connected to the bottom of the arrester I0. A line I8 leads from the bottom of the arrester II to the bottom of a clay-treating tower I9, and a pipe 20 having valves 2|, 22 and 23 leads from the upper part of the clay, tower I9 to the inlet end of a heating coil 24y located in a cooler portion of the furnace 8. A line 25 controlled by a valve 26 connects the outlet end of the heating coil 24 to a fractionating tower 21. A by-pass 28 controlled by valve 29 connects lines 20 and 25. A line 30 having a valve 3| connects the line 25 to a second fractionating tower 32. A line 33 havinga valve 34 connects the top of the fractionating tower 21 with the line 30. A draw-off line 35 having a valve 36 leads from the bottom of tower 21. A by-pass 31 controlled by valve 38 connects lines 20 and 38.

From the bottom of the fractionating tower 32 a pipe 40 having valves 4I, 42 and 43 and having a pump 44 connected therein leads back to and connects with pipe 2 at a point between the high pressure pump 5 and the heating coil 6. A bypass" 45 controlled by valve 46 is connected in the line 40 around the pump 44. A withdrawal line 41 having a valve 48 is connected to the line 40 betweenthe bottom of the tower 32 and the valve 4I. A by-pass 50 connects line 40 with the line 2 before the booster pump 4, and a by-pass 5I 1 connects line 40 with pipe 2 between the booster to a high-pressure separator 58. A pipe 59 having a valve 60 is connected to the top of the separator 58 and leads to a gas-recovery plant (not shown). A pipe 6I having a valve 62 connects the upper part of the high-pressure separator 58 to the upper part of a low-pressure separator 63. The separator 63 may be made to serve as a stabilizer by providing a heating coil in the bottom, a cooling coil at the top, and fractionating plates between the coils, (none shown). A pipe 64 leads from the upper part of the low-pressure separator 63. A pipe 65 having a valve 66 leads from the low-pressure separator 63 to a suitable storage tank 61. Connected to the lower portions of the separators 58 and 63 is a pipe 68 having valves 69 and 16. A pipe 1I is connected to the pipe 68 between the valves 69 and 10. A booster pump 12 and a high-pressure pump 13 are connected in the line 1I. The pipe 1I has a valve 11 and leads to the upper portion of the arrester II. A tank 18 is connected by means of a line 19 having a valve 86 to the line 1I at a point between the pipe 68 and the pump 12.

The following is a speciiic example illustrating my process as it may be carried out in the apparatus shown in Fig. l, but `it will be under.- stood that the specific conditions herein recited may vary in accordance with the nature of the materials treated and the results desired. The process is carried out as follows:

Suitable charging stock, for example a straight-run heavy naphtha having an initial boiling point of from 250 to 350 F. and an end boiling point of from 400 to 500 F. is raised by the booster pump 4 and the high pressure pump 5 to a pressure of from 750 to 2000 pounds per square inch and sent through the heating coil 6 where it is heated to a temperature of from 925 to 1050 F. The products emerging from the coil 6 are then passed through the line 9 into the arrester II where they are chilled to a temperature of from 550 to 650 F., preferably from 575 to 600 F., by contact with finished distillate returned from low-pressure and high-pressure separators 63 and 58, or by means of untreated distillate obtained from a cracking operation, stored in tank 18. The distillate used for chilling is raised to a pressure above that maintained in the arrester II by means of pumps 12 and 13. The pressure in the arrester II is substantially the same as that existing in the coil 6. From the arrester II, the total products are passed upwardly through a bed of clay or other similar adsorptive catalyst or polymerizing agent contained in the tower I9, preferably without reduction of pressure other than that incident to passage of the products through the catalyst, and wholly or largely in the liquid phase. The products leaving the clay tower I9 are preferably reduced in pressure, for example to a pressure of 40 pounds per square inch, or more, by means of valve 2|, valve 38 or valve 22, and then may be passed either through heating coll 24 where the temperature of the oil is raised to approximately 700 F. and then into the fractionating towers 21 or 32, or they may be passed by `tion' of heat.

way of line 31 into tower 32, or by way of line 28 into tower 21 without additional heating, depending on whether or not the temperature of the products leaving the tower I9 are at sufciently high temperature to effect vaporization of the desirable fractions without further addi- If desired, a portion of the products leaving v the clay tower may be passed through the heating coil and the remaining portion may be passed directly into either or both towers 21 and 32. Where the products are ilrst passed through fractionator 21, the light fractions or overhead vapors may be taken off as vapor and further fractionated in tower 32. Recycle stock is removed from the bottom of the tower 3 2 through the line 40 and the light fractions pass overhead through the line 55 to the condenser 56. The mixture of condensate, gas and uncondensed vapors then passes into the high-pressure separator-58, which may be maintained under a pressure of, for example, approximately 40 pounds per square inch, although this pressure is not limited and may be increased or decreased as desired. Gas and uncondensed vapors are withdrawn through the line 59 controlled by valve 60 and may be taken to the gas-recovery plant (not shown) where the condensable portions thereof are recovered. Condensate from the. high-pressure separator 58 then,passesinto the low-pressure separator 68, wherein a low pressure' of, for example, atmospheric to 10 pounds per square inch gauge, is maintained, and the gases-which separate are taken off through the4 pipe 6'4 and may be disposed of in any suitable manner as, for example, by being burned as fuel in the furnace. The low-pressure separator may, as aforesaid, contain fractionating plates, a heating coil in the lower part and a cooling coil in the upper part, (none shown) and thereby function as a stabilizer for the liquid before it passes to storage through the line 65.

A portion of the condensate in the lowand high-pressure separators may be continuously withdrawn and raised to the pressure existing in the arrester by means of the booster and highpressure pumps 12 and 13 and sprayed into the top of .the arresters through the pipes 14 and 15, respectively.

The pressure in towers 21 and 32 may range from 0 to 150 pounds per square inch, but preferably will be between 40 and 50 pounds per square inch. The temperature of the vapors entering tower 21 may be approximately 700 F., and the temperature of the vapors entering tower 32 may range from 550 to 700 F. A portion of the condensate from tower 32 may be recycled back to heating coil 6. The pressure in the tower 32 and the operation of the pump 44 will determine to what point in the line 2 the recycled stock is returned. If the pressure is near atmospheric, the condensate will be sent through by-pass 50 back to line 2. If the pressure in tower 32 is sufficiently high, the condensate may pass through by-pass 5I to the line 2, or the recycled stock may pass through pump 44 where its pressure is raised suillciently to inject the condensate into the pipe 2 between the high pressure pump 5 and the heating coil' 6. The condensate from tower 32 may or may not be recycled ormay be partially recycled. The portion not recycled is withdrawn through the line 41. Liquid collected in tower 21 is withdrawn from the system through draw-oil pipe 35.

Instead of using the rened distillate from the lowand high-pressure separators as chilling stock, rened or untreated distillate, preferably the gasoline fraction, from a vapor-phase orv will be understood, however, .that heavier fracoils from the oils charged to the coil |2|, as in a conventional cracking operation, but to effect a molecular rearrangement, ordinarily known 'as reforming, 'of the hydrocarbons of the oil from the paramnic saturated lorder into oils containing large percentages of unsaturated aromatic compounds, and to do this with as little formation of fixed gas as is possible. Some adjustment of temperature and pressure conditions within the limits above specified should be eiected, depending upon the character of the naphtha used as charging material for the purpose of securing the best results. Such adjustment is, of course, within the skill of the ordinary worker in the art.

The reformed unsaturated oils produced by the operation of the still or converter |22 requires some treatment for stabilization purposes before the oils can be used as a completed motor fuel. It has been observed that certain types of unsaturates, especially the dioleiines, readily oxidize when exposed to air, and sometimes light, to produce high-boiling compounds known as polymers. 'I'hese polymers comprise gum-like particles of matter which if permitted to remain in the oil would interfere with its utility as a motor fuel. To effect the removal therefore of these undesirable polymers, the oils or vapors discharged from the coil |2| preferably pass by way of a transfer line |24, lines |25 and |26.into treating chamber or clay tower |21. The line |25 is controlled by valve |28 and the cooler |23 is placed in the line to cool the oil land/or vapors leaving the coil |2| to a temperature suitable for clay treatment. The line |26 is controlled by pressure release valve |30 to lower the pressure on the products passing into the clay tower in order that they may pass through the tower in the vapor state. The products leaving the' heating coil |2| instead of passing through line |25 may pass through line |3| controlled by valve |32 in which is placed the shock chiller or arrester |33. Any suitable oil such as disclosed in connection with the arrester in Fig. 1 may be used as chilling medium in the chiller |33. If desired,` the products issuing from coil |2| may be passed through lines |25 and |3| simultaneously. In the chamber 21 there is arranged an adsorptive catalyst f the nature of fullers earth, which is designated by the numeral |34. The vapors upon contact with the catalyst are below a cracking temperature and may be under pressure of several hundred pounds. Under these conditions of elevated temperature and pressure, the fullers earth, bentonite, silica gel, or diatomaceous earth constituting the bed in tower |21, polymerize undesirable unsaturated compounds contained in the vapors into higher boiling compounds known as polymers. These polymers possess a boiling range higher than that of the oils or vapors charged to the chamber 21, indicating the polymerized character thereof.

Following contact with the catalyst |34, the treated oils are passed through line |35 controlled by valve |36 into a separator |31, where the light treated vapors are separated from high-boiling liquid oils. The vapors are drawn off through an overhead line |38 and pass through a cooler or condenser |39, thence through a look-box |40, a gas separator |4|, and iinally delivered to a storage tank |42 as treated end point motor fuel distillate. The high-boiling liquid oils are removed from the bottom of the separator through a draw-off line |43 controlled by valve |44.

It will be understood that a pair or plurality of the chambers |21 may be provided, whereby when the catalyst in'any one of such chambers the fractionating tower |06 is provided with a L draw-oil. line |49 for the discharge of liquid high-boiling oil. These oils may be usually employed as charging stocks for associated cracking systems.

It will be seen that I have invented a novel process and apparatus which provides economical operation for producing a nished motor fuel of high anti-detonating value from which the gum-forming constituents have been removed, while avoiding formation ofV undesirable heavy residues and large gas losses.

This application is a continuation in part of my co-pending application Serial No. 595,585 led February 27, 1932.

What is claimed is; y 1. The method of preparing gasoline of high anti-detonating characteristics and low gumforming content from naphtha of low anti-detonating characteristics, which comprises heating the naphtha in a restricted stream to a temperature of approximately 1000 F. under a pressure of approximately 1000 pounds per square inch, immediately thereafter suddenly chilling the resulting products to a temperature below conversion temperature and without substantially reducing the pressure thereon, passing the entire resulting products in the absence of added hvdrogen through an adsorptive catalyst capable of polymerizing substantially only the objectionable unsaturated constituents into high-boiling hydrocarbons, fractionating the treated products to remove relatively high-boiling products for a period suiiicient to eect the desired improvementl in the anti-knock characteristics, thereafter suddenly cooling the resulting 'products to a temperature below the conversion temperature but above vthe normal vaporizing temperature, thereafter contacting the total resulting products in the absence of added hydrogen l with an adsorptive catalyst capable of polymerizing substantially' only the objectionable un-l saturated constituents into high-boiling hydrocarbons, fractionating the treated products to vremove constituents above the gasoline boiling range and separately condensing and collecting 70Loss tions such as kerosene or even gas oil may oe used as chilling stock. Untreated distillate introduced in this manner is of course rened along with the stock from the reforming coil t.

When cracking heavier oils such as gas oil and re-cycle stock into lighter fractions, it may in some instances be advantageous to use two arresters. In the rst arrester l the conversion products are chilled to a temperature of approximately 700l to 800 F. in order to arrest the conversion reaction and to knock out heavy fuel oil which may form as a result of the conversion operation. The fuel oil will be withdrawn from the system through the valve controlled pipe i0. The uncondensed lighter fractions pass from the arrester l0 into the arrester il where the ternl perature is reduced to from 550 to 550 F. and sent through the clay tower. When operating in this manner the arrester il serves as a chlller or cooler to bring the products leaving arrester l0 to a temperature suitable for the clay treatment. From the clay tower the products are preferably passed through the heating coil 20 into the fractionating tower 2l to remove the heavy ends which are withdrawn therefrom through the valve controlled pipe sti. IThe vapors then pass into the second fractionating tower 32 where they are further separated into finished overhead stock and condensate for recycling. It will be understood, however, that when treating oils heavier than naphtha, such as kerosene or gas oil, the total products from the cracking coil may be passed through the clay tower.

The clay tower is preferably insulated to maintain the temperature at which the products enter and also in order to avoid to a large extent, subsequent heating for fractionation of the resulting products. Due to the exothermic reaction in the tower, the temperature may rise slightly.

The following data are the results of actual operations:

Straight run heavy naphtha Straight run Gas o gasoline 2500 bbls. l2 min 3700 bbls.

Chargeper unit day Total 7.4 min.

ature. Still outlet oil temperat e Cooling oil charged to arrester.

`Temperature of products entering clay tower.

Temperature oi products leaving clay chamber.

Pressure distillate yield (gasoline).

8 min 4 min 5.5 min.

1.9 min.

1100 lbS.

750 lbs. 950 lbs.

700 lbs.

43 lbs.

37 lbs.

Atm.

1200/1500" F. Atm.

Atm

l 200/l500 F Atm Atm 12m/1500" F. Atm

3350 bbl5 2500 bbls 3200 bbls.

15F v59o" F 610 r.

Time ol contact in clay tower.

Octane number before treatment.

Octane number of gasoline after treatment.

lit will be noted from the above data that the reforming temperature for straight run naphtha is only 950 F. in this instance the main object was to adjust the boiling range of the naphtha without obtaining a large increase in anti-detonatlng characteristics.

t will also loe noted that the pressures in the clay towers are somewhat lower than the still pressures. This drop is due to the line drop together with the cooling of the oil effected in the arrester.

Although temperatures of 925 to i050u F. have been indicated for the conversion step, it will be understood that temperatures as low as 850 F. and as high as l300 F. may he used, depending on the oil to be treated and the results desired. The pressure should he at least sumcient to main tain the oil substantially in the liquid phase during the clay treatment.

Referring to Fig. 2, the numeral idg designates a tank or other container adapted for the reception of crude oil from which leads a pipe line G02. Arranged in the pipe line is a pump 503 for advancing the oil under pressure through the heating coil U00 of a skimming or topping still |05. During the passage of the oil through the coil |00, the said oil is heated sumciently to vaporize its lower boiling compounds up to and including the naphthas or kerosene contents thereof. The heated oils discharged from the coil l 00 pass into a fractionating tower |06, which is operated at temperatures permitting of the withdrawal as vapors of light naphtha from the top of the tower. The vaporized light naphtha travels through an overhead pipe line |07 Sand is condensed in the cooler |08 and delivered to a separator |09. A gas line leads from the top of the separator and the light naphtha is drawn oi from the bottom of said separator through a oat valve control line ill passing through a look-box H2 and thence to a storage container H3.

From the side of the tower |05, at a position midway of its height, there is provided a lateral draw-off line iid through which a condensate in the form of heavy naphtha is removed from the tower. Thus condensate is passed through a cooler l l5, thence through a look-box H6 to a container lil. It is to theytreatment of this heavy naphtha as received Within the container M1, that the present invention is particularly directed.

Leading from the container H1 is a transfer line H8 which is provided with a valve H9 and a pump which is employed to force the heavy naphtha', withdrawn from the tank H1, through the heating coil |2| of a conversion furnace |22. The furnace |22 may be of any standard con- L,struction including outer heat retaining walls and provided with one or more burners |23 for the development of heated gases of combustion which are used in raising the temperature of the oil passing through the coil |2| through reforming or converting temperatures. Usually, these temperatures vary between 1000 to 1350 F., or inv other words, typical vapor phase converting temperatures. The pressures in the coil |2| may vary from slightly above atmospheric to pressures of the order of several hundred pounds per square inch, and preferred pressure range va. ries between 300 to 800 pounds per square inch. 'Ihe vaporized oils passing through the coil I2! are therefore subjected to conversion conditions, that is to say, no eiort is made to eiect the formation of considerable quantities of lower-boiling gasoline constituents as a final product of the process.

4. A method of improving the anti-knock properties and stability of motor fuel which comprises heating a light hydrocarbon oil having low anti-knock properties consisting principally of constituents within the gasoline boiling range to a. cracking temperature adequate to improve the anti-knock characteristics of said oil, maintaining said oil at said cracking temperature for a period sufficient to improve the anti-knock properties thereof to the desired extent, thereafter suddenly cooling the resulting products below active cracking temperature but above the normal vaporizing temperature of the original oil, contacting the total products in the absence of added hydrogen while at said reduced temperature with a solid adsorptive catalyst capable of polymerizing substantially only the objectionable unsaturates for a period adequate to form a stable gasoline product, thereafter fractionating the treated products into a high-boiling fraction above the gasoline boiling range and a fraction within the gasoline boiling range and removing said last-named fraction as a final product of the process.

5. A method of improving the anti-knock properties and stability of motor fuel which comprises heating a heavy naphtha fraction consisting principally of higher-boiling constituents of gasoline having relatively low anti-knock properties to a temperature between 925 F. and l050 F. While under a pressure between 750 and 2000 pounds per square inch, maintaining said heavy naphtha at said elevated temperature and pressure for a period adequate to improve the antiknock properties thereof the desired amount, thereafter suddenly cooling the resulting products to below cracking temperature but above the normal vaporizing temperature of said heavy naphtha, contacting the total resulting products in the absence of added hydrogen while at said reduced temperature with a solid adsorptive catalyst capable of polymerizing substantially only the objectionable color-imparting and gumforming constituents thereof and thereafter separating a fraction within the gasoline boiling range from the products so treatedas a final product of the process.

6. A method of improving the anti-knock properties and stability of motor fuel which comprises heating a light hydrocarbon oil having low anti-knock properties and consisting principally of constituents boiling within the gasoline and kerosene boiling range to a cracking temperature adequate to reform the gasoline constituents to improve the anti-knock properties thereof, maintaining said oil at said cracking temperature for a period adequate to improve the anti-knock properties to the desired extent, thereafter commingling the resulting products with a relatively cooler stream of light hydrocarbon oil consisting principally of constituents within the gasoline and kerosene boiling range to suddenly reduce the temperature of the heated products to below cracking temperature but above the normal vaporizing temperaturethereof, thereafter contacting the total mixture in the absence of added hydrogen with a solid adsorptive catalyst capable of polymerizing substantially only the objectionable color-imparting and gum-forming constituents thereof, fractionating the products resulting from said last-named treatment to separate a fraction within the gasoline boiling range as a nal product of the process.

'7. A method of improving the anti-knock properties and stability of motor fuel which comprises heating a light hydrocarbon oil consisting principally of gasoline and kerosene constituents to a cracking temperature adequate to reform the gasoline constituents into products of improved anti-knock properties, maintaining said oil at said cracking temperature under a superatmospheric pressure, subjecting said oil to said high temperature treatment for a period adequate to improve the anti-knock properties thereof the desired extent, thereafter admixing the resulting heated products with a low temperature, light hydrocarbon oil having low anti-knock characteristics and consisting principally of constituents Awithin the gasoline and kerosene boiling range to suddenly reduce the temperature of the heated products to below cracking temperature but above the normal vaporizing temperature thereof, thereafter contacting the total resulting mixture in the absence of added hydrogen with a solid adsorptive catalyst capable of polymerizing substantially only the objectionable color-imparting and gum-forming constituents and fractionating the products resulting from said last-named treatment to separate a distillate within the gasoline boiling range.

8. A method of improving the anti-knock prop- `erties and stability of motor fuel which comprises heating a light hydrocarbon oil consisting principally of gasoline constituents to a cracking temperature adequate to reform the gasoline constituents into compounds having improved antiknock properties, maintaining said oil at said cracking temperature for a period adequate to improve the anti-knock properties thereof the desired extent, thereafter admixing said oil with a relatively cooler light hydrocarbon oil having low anti-knock properties to suddenly reduce the temperature of the heated products to below cracking temperature but above `the normal vaporizing temperature thereof, thereafter contacting the total mixture in the absence of added hydrogen with a solid adsorptive catalyst capable of polymerizing substantially only the objectionable color-imparting and gum-forming constituents, maintaining said mixture while in contact with said solid adsorptive catalyst under a pressure adequate to maintain a substantial portion of said mixturein liquid phase and fractionating the products resulting from the last-named treatment to separate a motor fuel within the gasoline boiling range.

9. The method of improving the anti-knock properties and stability of motor fuel which comprises heating a light hydrocarbon oil having low anti-knock properties consisting principally of constituents within the gasoline boiling range to a cracking temperature adequate to improve the anti-knock characteristics of said oil while being maintained under superatmospheric pressure, maintaining said oil at said cracking temperature and under said-superatmospheric pressure for a period suflicient to improve the anti-knock properties thereof, suddenly cooling the resulting.

products at substantially said pressure to a temperature below cracking, contacting the total resulting products while at said reduced temperature, without reduction of pressure and in the absence of added hydrogen, With a solid adsorptive catalyst capable of polymerizng substantially only the objectionable unsaturates, thereafter fractionating the treated products into a high-boiling fraction above the gasoline boilingk range and a fraction within the gasoline range, 11. The method in accordance with claim I and recovering said last-mentioned fraction. wherein the light hydrocarbon oil used to sud- 10. 'I'he method in accordance with claim 6 denly reduce the temperature of the heated prodwherein the light hydrocarbon oil used to sudducts is an untreated light oil containing co1ordenly reduce the temperature of the heated prodimporting and gum-forming constituents.

ucts is an untreated light oil containing colorimparting and gum-forming constituents; RUDOLPHI C. OSTERSTROM. 

